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Compressed Natural Gas (CNG) Safety Assurance

CNG Safety Assurance Project Webinar April 11, 2017

National Renewable Energy Laboratory (NREL) Supporting the U.S. DOE Clean Cities Program

Kay Kelly & John Gonzales

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Topic CNG Basics Safety Assurance Project Background CNG Maintenance Requirements Fuel Tank Code & End of Life Requirements Defueling, Decommissioning and Disposal Video Additional CNG Safety Assurance Efforts Underway Q&A

AGENDA

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Natural Gas •  Hydrocarbons, predominantly methane (CH4)

•  High octane rating

•  Nontoxic, noncorrosive, and noncarcinogenic

•  Not a threat to soil, surface water, or groundwater

•  Conventional natural gas is extracted from gas and oil wells

•  Renewable natural gas can be produced from landfills and livestock operations

•  Existing pipeline distribution system

Natural Gas

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Compressed Natural Gas (CNG) •  Stored in onboard tanks under high

pressure •  Fuel economy similar to gasoline •  1 GGE = 5.7 lb CNG

Liquefied Natural Gas (LNG) •  Kept at cold temperatures •  Stored in double-wall, vacuum-insulated

pressure vessels •  Heavy-duty vehicles •  1 GGE = 1.5 gal LNG

Natural Gas: CNG and LNG

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Vehicles: Applications

Light-Duty •  Passenger cars and

light-duty trucks in private and government fleets

•  Personal vehicles

Medium-Duty •  Vans and shuttles •  Airports and taxi fleets

Heavy-Duty •  Refuse haulers •  Transit buses •  School buses •  Long-haul trucks •  Street sweepers •  Snowplows •  Short-haul delivery

trucks

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•  NGV Industry stakeholders meet regularly to discuss and address technical concerns, including those related to CNG fuel tank safety standards, periodic inspections and end-of-life disposal requirements

•  A Transit Authority contacted DOE to look for assistance/direction on 160+ CNG buses with tanks that were approaching their expiration date and this experience was the catalyst to develop additional information for fleets with aging CNG fuel tanks

•  To ensure safe operation and decommissioning of these fuel tanks, a government-industry partnership began to develop resources related to training, best practices, case studies, and general outreach/awareness.

CNG Safety Assurance Project Background

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CNG Tanks and Safety

Helpful Resource:

When properly operated and maintained, natural gas infrastructure and vehicles are unlikely to present any danger to drivers or passengers. NFPA 52, the

Vehicular Gaseous Fuel Systems Code, spells out specific safety requirements for natural gas vehicles (NGVs) and their fueling facilities.

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•  CNG Fuel Tanks (Cylinders) shall be manufactured, inspected, marked, tested, equipped and used in accordance with ANSI NGV 2 or FMVSS 49 CFR 571.304. NFPA 52 allows either standard.

•  Fuel Tanks should be visually inspected at least every 36 months or 36,000 miles, whichever comes first, and; -  After a motor vehicle accident or fire and; -  After a dispenser malfunction that results

in pressure greater than 125% service pressure.

CNG Code Requirements: Periodic Inspections

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Importance of Inspections After Accidents/Incidents

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CNG Code Requirements: End of Life

•  Fuel Tanks that have reached their labeled expiration date (EOL) or been condemned by inspection shall be removed from service (and destroyed).

•  All CNG fuel tanks carry a label that says "DO NOT USE AFTER (EXPIRATION DATE).”

•  CNG fuel tanks have a useful life of 15, 20, or 25 years, depending on their construction and how they were certified by the original manufacturer.

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•  In December 2015, LAMTA hosted a Clean Cities technical assistance team to observe their CNG fuel tank defueling, decommissioning, disposal and replacement process.

•  The team included representatives from NREL, CSA Group, Agility Fuel Systems, Gladstein, Neandross & Associates (GNA), and U.S. Department of Transportation-Volpe Center.

LA Metro Site Visit

•  The process used by LA Metro was videotaped and is the basis of a training video developed by NREL for transit agencies and other CNG fleets.

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CNG Defueling, Decommissioning and Disposal Video

Chapters •  Introduction •  Defueling •  Decommissioning •  Disposal

https://youtu.be/vTxQPfsm8n0

www.cleancities.energy.gov

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1.  Inspection of Fuel System –  Wear personal protective equipment –  Follow manufacturer guidelines –  Use properly trained technicians –  Inspect tank, valves, fittings and

mounting hardware for damage/leaks

2.  Defueling Tank –  Defuel while tank is still secured on the vehicle –  Earth ground the vehicle –  Ensure a proper connection between vehicle and fuel panel

•  Defueling time ranges from 1-12 hours depending on tank size/configuration

–  Use gauge to check pressure –  Vent any residual gas remaining in tank

3.  Verify and Document Completed Defueling

Defueling

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•  Defuel to Another Vehicle •  Defuel to Storage •  Vent Stacks •  Flare Stacks

Defueling Options

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1.  Verify Completed Defueling 2.  Remove Valve from Tank

–  Wear personal protective equipment –  Follow manufacturer recommended procedures –  Disconnect lines & fittings before removing valve –  Ensure technician is not in direct line with the

valve as it is removed 3.  Remove Tank from Vehicle

–  Remove tank mounts –  Remove tanks individually or as an assembly

4.  Purge, Destroy and Decommission Tank –  Purge with Nitrogen to drive out any residual

natural gas –  Drill ½” holes to prevent re-use –  Mark tank label to indicate that it is decommissioned

5.  Verify and Document Completed Decommissioning

Decommissioning

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1.  Verify Completed Decommissioning 2.  Properly Dispose of Tanks

–  Follow manufacturer recommendation –  Some tank materials can be recycled

3.  Document Completed Disposal

Disposal

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Key   industry   stakeholders   have   developed   a   CSA  Express  Document  that  will  serve  as  a  bi-­‐na/onal  publica/on   for   the   safe   decommissioning,  defueling  and  disposal  of  CNG  storage  vessels.    

The  Express  Document  will  be  referenced  in  exis/ng  Codes  and  Standards  and  is  available  for  purchase  at  www.csagroup.org        

Target  users  include  the  general  public,  CNG  and    LNG  fleets,  emergency  responders,  disposal  centres  and  AuthoriCes  Having  JurisdicCon  (AHJ’s).      

The  Express  Document  is  intended  to;  •    increase   awareness   of   safe   prac/ces  

pertaining  to  the  decommissioning,  defueling  and  disposal  of  CNG  and  LNG  storage  vessels.    

•  alert  technicians,  owners  and  recyclers  to  the  poten/al  hazards  and  safe  prac/ces  

EXP2.1,  Defueling,  Decommissioning  and  Disposal  of  Containers  

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•  End of Life CNG Tank Testing Effort –  NREL is evaluating a cross-section of CNG fuel tanks that are leaving

service at end of life based on existing tank standards –  Results of this testing will be shared with industry to continue to validate

and improve tank safety standards

•  CNG Incident Investigation Process Improvements –  Collaboration between the U.S. Department of Transportation National

Highway Traffic Safety Administration (NHTSA), Natural Gas Vehicles for America (NGVA) and Clean Cities Tiger Team technical experts

–  Evaluate CNG incidents to determine root cause and recommend best practices that will prevent future incidents

•  CNG Maintenance Facility Modifications –  Handbook for fleet managers in development, anticipated publication –

summer 2017 –  Development of risk-informed guidelines for maintenance facility design

and operation

Additional CNG Safety Assurance Efforts

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www.afdc.energy.gov

Alternative Fuels Data Center (AFDC) CNG Resources

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Clean Cities Website: www.cleancities.energy.gov

Alternative Fuels and Advanced Vehicles Data Center: www.afdc.energy.gov

Fuel Economy: www.fueleconomy.gov

Clean Cities Coordinator Contact Information and Coalition Web Sites: www.afdc.energy.gov/cleancities/progs/coordinators.php

Clean Cities Technical Response Service: technicalresponse@icfi.com, 800-254-6735

Kay Kelly National Renewable Energy Lab

Clean Cities (303) 384-7554

Kay.Kelly@nrel.gov

John Gonzales National Renewable Energy Lab

Clean Cities (303) 275-4393

John.Gonzales@nrel.gov

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Question and Answer Session

Please type your questions into the question pane on the control panel